Tubular unit for boiler walls



Dell 5, 1939. T E MURRAL JR 2,181,950

TUBULAR UNIT FR BUILER WALLS Filed March 2l, 1936 l 000001;` w 00000l INVENTOR.

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ATTORNEYS Patented Dec. 5, 1939 UNITED STATES PATENT OFFICE 9 Claims.

, .pension like gas, oil, or powdered coal, particu- 10 larly the last.

When using powdered coal there is a certain quantity of ash which is incombustible but is` melted or softened in the flame and is deposited on the walls.

The present invention provides a style of Wall and a tubular unit for building the same in which special provision is made for keying or anchoring to the wall the slag or ash which is deposited there in the operation of the furnace. The -same 20 construction is useful in case it be desired to cover the face of such a water Wall with refractory material applied deliberately and before putting the furnace to use.

Referring to the embodiments of the invention 25 illustrated- Fig. 1 is a horizontal section through one of the tubular units. Fig. 2 is a face elevation of a portion of such a unit. Fig. 3 is a similar view illustrating a slight modication. Fig. 4 is a l similar fragmentary view of another modification. Fig. 5 is a horizontal section of a portion of a water wall. Fig. l6 is a vertical section on an enlarged scale on'the line 6-6 of Fig. 5.

Referring first to Fig. 5, a water wall vor screen 55 is made' of a succession of tubes IV `placed alongside of each other and spaced apart slightly, having fins 2 extending into the spaces between them and practically filling the width of such spaces. These are backed by a wall of-refractory bricks l0 3, generally with a plastic lling 4 of even greater refractoriness in the spaces between the bricks 3 and the fins. The wall is completed by an outer layer of insulating material 5 and a metal casing 6 holding the refractories in place.

L On the inner, or fire, side of the wall of water tubes is a coating 1 of highly refractory material which has the advantage of. shielding the tubes to some extent and preventing overcooling of the `flame, and also of maintaining an incandescent surface in operation which may be beneficial in securing complete combustion of the fuel. This coating 1 may be applied to the face of the water wall by hand or may be accumulated thereon 5 from molten slag or ash. And even if such a coating be applied beforehand it will collect'additional molten slag or ash.v

For keying the plastic coating and holding it in placethe fire face of the ns is formed with openings or recesses. This keying is sufficiently ..5

`strong to hold 'not only the coating which isv in direct contact with the fins but also that which spreads over the plain face of the tubes. The natural slight roughness of the tubes is assisted by the recesses in the fins. The recesses may be .10 of various sizes and depths and locations .and may be secured by various constructions.

In previous patents, for example, Murray Patent 1,886,214, November 1, 1932, apertured flanges have been applied to boiler tubes for keying to l5 them a plastic outer portion of the wall. The present invention, however, is for a very diierent purpose, the keying of a refractory coating on the fire-side of a tubular water wall. And for this purpose the ns, as shown in Fig. 5, are located inward (that is toward the fire-side) at least as far as the line through the centers of the tubes. In this line they are close enough to the inner faces of the tubes themselves to hold the plastic coating on the tube face as well as on the fins.

According to Fig. 1, a number of 'iin segments 8 are welded separately to the tube as at 9. The segments have considerable width (radially of the tube) `but comparatively little length along the tube and little thickness so that the welded joint is a separate one for each n segment. The segments are spaced close together, however, so as to secure the practical effect of a fin which is continuous in the lengthwise direction of the tube and forms with the tubes themselves a practically continuous metallic wall exposed to the lire.

By makingvthe ns in small segments separately welded we avoid the distortion and strains which have occurred in tubes and iins themselves 40 when made in substantially continuous lengths and welded along their entire lengths. Also each small iin segment is capable of distortion under the heat of use separately from the others and without putting any strain on the others. 45

The projection or fin segment 8 is bent around at its outer end as shown at Fig. l and brought back to the tube and welded thereto at I0 at the same time as at 9. The front portion of the strip, however, is provided with a number of perforations Il which in the finished shape of the fin constitute recesses extending half way through the depth thereof.

In Flg. 1 there are three such recesses along the length of each segment. According to Fig. 3 55 there are ten recesses Ill similarly produced but smaller and closer together.

According to Fig. 4 the recesses Ilh are half round perforations on the top and bottom edges.- The eiect is substantially the same in any of these cases.

'I'he term recesses" is used herein to define openings in the faces and extending only partly through the ns into which the plastic material can enter a sumcient depth to key and hold it in place while the faces of the ns between the recesses are smooth.

It is not only the circular recesses Il illustrated in the faces of the ns which grasp and hold keying portions of the plastic coating as illustrated at I2, Fig. 6. The spaces extending clear through from front to back between the separate segments B also serve to' receive and hold key portions i3 of the plastic coating 1 and thus supplement the recesses Il.-

The fused slag from the burning fuel varies in quantity and in consistency withI different fuels. Diii'erences are found also when running the furnace hotter or cooler. Differences, of course, may be made in the character of coatings applied before ring the furnace.

'I'he recesses are designed to take care of these varying conditions in thev coatings. The spaces between the iin segments 8 are so close to each other (that is the length of the segments is so slight) that the keys formed in such spaces or recesses will hold a very considerable weight of plastic coating so as to supplement the weightsupporting eect of the recesses in the faces of the fins. l

'Various other modications may be made by those skilled in the art without departing from the invention as defined in the appended claims.

What I claim is:

1. A unit for building walls of boilers and the like comprising a tube having a longitudinal n which is welded directly to the tube and whichis formed with recesses open on one face only and adapted to receive portions of a plastic coatingv so as to key the coating and hold it in place.`

2. A unit for building walls of boilers and the like comprising a tube having a longitudinal n which comprises an integral piece of metal with recesses open on one face only and adapted to receive portions of a plastic coating so as to key the coating and hold it in place. Y'

v3. A unit for building walls of boilers and the like comprising a tube having a longitudinal nwhich comprises a metal strip with recesses in it open on oneface only and adapted to receive portions of a plastic coating so as to key the coating and hold itin place.

4. A unit for building walls of boilers and the like comprising a tube having a longitudinal iin which comprises a multiple-ply metalu strip, one

v ply constituting a face intended for exposure to the ilre and having holes through it which are adapted to receive portions of alplastic coating so as to key the coating and hold it in place.

5. A unit for building walls of boilers and the ylike comprising a tube having a longitudinal iin made of separate closely spaced segments the faces of which have recesses open on one face only and adapted to receive portions of a plastic coating so as to key the coating and hold it in place, the spaces between the segments serving also to key the coating4 and help to hold it in I place.

v 6. A unit for building walls of boilers and the like comprising a tube having a longitudinal fin made of separate closely spaced segments each of which comprises a metal strip with recesses in it open on one face only and adapted to receive portions of a plastic coating so as to key the y coating and hold it in place.

'1.v A unit for'building walls of boilers and the like comprising a tube having a longitudinal iin made of separate closely spaced segments each of which comprises a multiple-ply metal strip, one ply constituting a face intended for exposure to the fire and having holes through it which are adapted to receive portions of a plastic coating so as to key the coating and hold it in place.

8. In a boiler wall the combination of a pluto hold it to the entire innerl face of the wall, in-

cluding the faces ofthe tubes between the ns as well as the faces of the 9. The boiler wall of claim 8, each of said ns being made of separate closely spaced segments, the spaces between which serve also to key the coating and hold it in place.

THOMAS E. MURRAY. JR. 

